A lid dropper is a piece of machinery that places lids on cans at a point along a conveyor after the cans have been filled with a product. It is known for automated equipment to place lids onto cans, such as for example paint can lids onto paint cans, by stacking lids in vertical alignment and holding the stacked lids in position by upright guide bars and a set of feed screws at the base of the guide bars, which support the stack of lids. The feed screws capture by rotation the lower lid from the stack and drop it onto an advanced can beneath the feed screws. The can is then indexed to a subsequent station where the lid is secured onto the can. The feed screws then rotate to capture the next bottom lid from the stack and drop it onto the next advanced can.
U.S. Pat. No. 2,184,029 of Wicklund discloses a can lid feeding unit that includes a set of four helical feed screw elements, each rotatably mounted on an inner end of a crank arm. A drive gear is associated with each feed screw element. Each crank arm is pivotal about a fixed shaft and is coupled to an intermediate gear, which couples each drive gear to an outer ring gear. A drive mechanism powers the ring gear to achieve rotation of each drive gear. The feed screw elements include a helical groove for capturing the rim of a lid and lowering the lid down onto a can.
U.S. Pat. No. 3,426,941 of Hovekamp discloses a similar feeder mechanism for stacked articles such as cans. Hovekamp includes in his apparatus a parallelogram linkage for each feed screw element and mounts a post at each feed screw element to support the stacked articles. Adjustment of the feed screw element also accomplishes simultaneous adjustment of the guide posts.
U.S. Pat. No. 3,712,483 of Messervey discloses a feeding device that utilizes an adjustable outer ring member that is coupled to a connecting rod linked to a swingable gear box housing that carries a grooved cam article advancing device. Rotation of the ring member swings the gear box housing and adjusts the relative spacing between the cam devices.
The foregoing patents are representative examples of prior art lid droppers. Unfortunately, however, these prior art lid droppers do not allow for the rapid and complete adjustment of the lid dropper assembly to accommodate lids having different diameters and cans of varying heights. Often, an entire production line must be shut down for a lengthy period of time while alterations are made to the lid dropper assembly or while alternative parts are installed, resulting in costly delays. Thus, there remains a need in the art for a fully-adjustable lid dropper that can be easily and rapidly adjusted to accommodate both different size cans and lids.
U.S. Pat. Nos. 5,476,362; 5,113,636; 5,494,399; 5,145,315; 4,623,057; 4,558,802; 4,243,153; 3,674,160; 3,253,722; and 3,776,420 are referenced for background purposes in order to put the present invention into proper perspective.